Oil containing rust inhibiting combination of two ingredients



rates Unite atent 3,036,969 Patented May 29, 1962 Fire of Delaware NDrawing. Filed Nov. 26, 1957, Ser. No. 608,937 6 Claims. (Cl. 252-325)The present invention is concerned with an oil containing twoingredients that in combination have surprising rust inhibitingproperties. More specifically, this invention proposes the synergisticcombinataion in an oil of minor amounts, under 0.2 weight percent each,of a branched alkyl mercaptoacetic acid and a non-emulsifying alkalineearth metal dialkylnaphthalene sulfonate to impart superior rustinhibition to the oil.

In brief compass, this invention proposes a lubricating compositioncomprising a major proportion of an oil of lubricating grade, and in therange of .005 to 1.0, e.g. 0.007 to 0.50, weight percent each of a C toC alkyl mercaptoacetic acid and an alkaline earth metal salt of adialkylnaphthalene sulfonate, wherein each alkyl group has from 6 to 12carbon atoms. The alkaline earth metal is preferably selected from thegroup of calcium and barium with the latter being most preferred, Thisrust inhibiting combination is particularly eflective when used inproportions of 3.0 to 0.3 parts by weight of branched alkylmercaptoacetic acid to 1 part by weight of alkaline earthdialkylnaphthalene sulfonate.

The mercaptoacetic acid used in the present composition has a formula:

wherein R is a branched alkyl group containing in the range of 9 to 17carbon atoms. In a preferred embodiment of this invention R is highlybranched. By highly branch d is meant that the alkyl radical contains atleast three forked or lateral groupings of one or more carbon atoms asside chains.

The particular naphthalene sulfonates used in this invention arecharacterized by the fact that in the concentrations used they do nottend to stabilize emulsions and in some cases actually act asdemulsifying agents. That is, they do not promote the formation ofstable emulsions as measured by the standard demulsibility test (ASTMD1401). Oils containing these naphthalene sulfonates do meet thelimiting requirement for Navy turbine oils of 3 ml. maximum lacy end in30minute as set forth in Specification MIL-L-17331A (Ships), The twoalkyl groups of the alkylnaphthalene sulfonate may be located in variouspositions on the rings, and are branched chain radicals having from C toC carbon atoms per radical. Particularly preferred are thedinonylnaphthalene sulfonates of the type described in US. Patent2,764,548.

The lubricating oil can be any conventional oil of lubricating gradeknown to the art, including animal, vegetable, synthetic and mineraloilsthe latter being preferred. Preferably the oil base has a viscosityin the range of 37 to 150 seconds, Saybolt Universal at 210 F., a flashpoint above 370 F., a pour point below 25 F., and a gravity in the rangeof 26 to 34 API.

Examples of suitable synthetic oils are diesters such as di-Z-ethylhexyl seb'acate; complex esters such a reac' tion products of 2 partsdi-2-ethyl hexanol, 2 parts dibasic acid, and one part polyethyleneglycol of about 200 average molecular weight; silicone oils such as thepolydimethyl siloxane Dow-Corning Fluid 200, prepared by hydrolyticcondensation of dimethyldichlorosilane; phosphorus derivatives such as COxo diphenyl phosphate and the. like.

The composition of this invention can also contain normal lubricatingoil additives in their customary proportions to impart certain desiredproperties. These additives are known to the art and include viscosityindex irnprovers, pour point depressants, extreme pressure agents,antioxidants, antifoamants and the like.

EXAMPLE I The base oil was derived from a Mid-Continent crude by phenolextraction, dewaxing by the MEK process with methyl ethyl ketone andclay contacting.

It has the following inspections:

Sulfated ash, weight percent 0.001 Sulfur, Weight percent 0.22

The additives were C Oxo mercaptoacetic acid and bariumdinonylnaphthalene sulfonate. The alkyl radicals of the mercaptoaceticacid were derived from C Oxo alcohol produced by carbonylation oftetrapropylene in the presence of a carbonyl catalyst, usually cobaltcarbonyl, with carbon monoxide and hydrogen at a temperature in therange of 200 to 400 C. and at a pressure of from to 300 atmospheres.After the carbonylation stage, an aldehyde having one more carbon atomthan the starting olefin is obtained, and this aldehyde is thenhydrogenated at temperatures of from 750 F. and at pressures of from100-300 atmospheres, in the presence of a hydrogenating catalyst(copper, nickel, etc.) to obtain the C Oxo alcohol. The C OX0 alcoholmay be converted to C Oxo mercaptoacetic acid by reacting with hydrogenbromide to form the bromide and treating the bromide with an alkalimetal mercaptan. The C OX0 mercaptan is then reacted with sodiumhydroxide. Monochloro acetic acid is added to this reaction mixture toproduce the C Oxo mercaptoacetic acid.

The barium dinonylnaphthalene sulfonate is prepared by alkylatingnaphthalene with highly branched nonenes, for example, tripropylene witha suitable catalyst, such as, hydrogen fluoride or anhydrous aluminumchloride in an anhydrous solvent containing in solution the naphthalene,Suitable solvents such as naphtha, sulfur dioxide, nitrobenzene or amixture of benzene and nitrobenzene in the alkylation result in a highyield of dinonylnaphthalene and relative ease of recovery of thesolvent. The dinonylnaphthalene is then dissolved in an organic solventwhich is substantially inert in its reaction with sulfuric acid and thesolution is sulfonated with oleum or sulfuric acid. Barium carbonate isreacted With the dinonylnaphthalene sulfonic acid to form the bariumdinonylnaphthalene sulfonate used in this invention.

Oil solutions were made up and tested in the MILL 17331A rust test. Thistest is the Standard ASTM sea water rust test (ASTM D665) and wascarried out after distilled water Washing of the oil sample at 90 C. for30 minutes (as required by MIL-L-17331A (Ships)).

The results are shown in Table I.

Table I shows that a surprisingly small amount of each of theingredients can be used in combination to give effective rustinhibition. These small amounts in com-" bination are equal or superiorto substantially larger amounts of each of the components usedseparately.

EXAMPLE II In some lubricating oils it is desirable to use zinc dialkyldithiophosphate as an antioxidant or extreme pressure additive. Somerust inhibitors of the free carboxylic acid type, including some verysimilar to the highly branched alkyl mercaptoacetic acid disclosedherein, form precipitates in the presence of zinc dialkyldithiophosphate, giving hazy blends and a partial loss of rustprotection. No such precipitate is formed by the use of the highlybranched mercaptoacetic acid (C Oxo SCH COOH) shown in the table below.The table shows a comparison between branched C13H2'7SCH2COOH and amercaptoacetic acid averaging n-C H SCH COOH, where the alkyl groupsrange from n-C H to H-C13H37.

Mixtnre of mercaptoacetic acids ranging from n-O HmSOOOH to n-CmH SCOOHand averaging H'OlQHflSCOOH.

?This additive is the same 0x0 mercaptoacetic acid as used in Example I.

EXAMPLE III The same base oil was used as in Example I. Samples weremade up with 0.35 weight percent of a zinc dialkyl dithiophosphate(where the alkyl groups are derived from a mixture of about 25 weightpercent isopropyl alcohol and about 75 weight percent methylisobutylcarbinol) to test the effectiveness of the rustinhibitingcombination.

The results are shown in Table III.

Table III Highly Branched Ba Salt of 13 0 9 2 SCHQCOOI'I) NaphthaleneMIL-Ir-I73S1A Mercaptoaeetic sulfonate Rust Test Acid (Weight (Weightpercent) 1 percent) 2 0. 04 Nil Fail (2% Rust). 0. 06 Nil Fail (1%Rust).

Nil 0. Fail (10% Rust). Nil 0.10 Fail 1% Rust). Nil 0.125 Pass (N 0Rust). 02 0. 05 Pass (No Rust).

1 This additive is the same mercaptoacetic as used in Example I. Thisadditive is the same sulfonate as used in Example I.

Table II points out that the combination of mercaptoacetic acid andsulfonate in accordance with the present invention gives equallyeffective rust inhibition to oils containing zinc thiophosphateadditives. The table also 5 points out that the combination permits goodrust inhibition at relatively low total rust inhibitor content and witha low level of free acid present. Thus, even when an excess of theinhibitors has been added as a margin of safety, the combination givesdesirable flexibility in pre- 10 paring blends to fulfill otherimportant requirements of quality, for example, low ash and lowneutralization number.

To demonstrate an interaction between rust-inhibiting components, lowlimiting concentrations, borderline in effectiveness, were testedexperimentally. In actual serv- -.ice, however, it is desirable to useconcentrations of rust inhibitors which will provide some margin ofsafety, concentrations which will still afford protection after somerust inhibitor has been removed as by plating out on metal surfaces orby very slow leaching of the inhibitors from the oil into water. Thefollowing examples show finished oil formulations incorporating the rustinhibitor combination of the invention in concentrations suitable forcommercial service.

EXAMPLE IV A marine extreme pressure turbine oil was formulated using aparafiinic type oil derived from a Mid-Continent crude by distillation,phenol extraction, MEK dewaxing with methyl ethyl ketone and claycontacting.

This base oil had the same physical properties as shown in Example I. I

The following ingredients were added to this base oil. 0.35 weightpercent of the zinc dialkyl dithiophosphate cited in Example III; 0.05weight percent of barium dinonylnaphthalene sulfonate (as 50%concentrate in Coastal oil) prepared as in Example I; 0.03 weightpercent C Oxo mercaptoacetic acid prepared as in Example 1; 0.0005weight percent Silicone antifoam agent (350 centistokes at 25 C.).

The finished inhibited formulation had the following inspections.

Viscosity, S.U.S., at 210 F 59.3. Viscosity, S.U.S., at 100 F 397.7.

Viscosity index 104.5.

Pour point, F. 20.

Neutralization number (ASTM D974) 0.8.1.

Sea water rust test (MIL-L-17331A) Pas (no rust). Oxidation life(ASTMD943) 1000 hrs.

Emulsion test (ASTM D1401) (3 ml.

max. lacy cutt' after 25 mins.) Pass. Mineral acidity (MIL-L17331A)Neutral. Copper strip corrosion (ASTM D130) (3 hours at 212 F.) 1(a).

Conradson carbon (ASTM D189) 0.16. Sulfated ash 0.14. Tag Robinson color13%. Mean Hertz load (VV-L-79l, 6503) 35.2 kg.

Ryder gear test (MILL17331A) 3310 lbs/inch.

Four ball wear scar (15 kg, 80 C.,

600 r.p.m., 2 hrs.) 0.27 mm.

This turbine oil is being field tested in a new 38,000 ton supertankerequipped with a 26,500 rated shaft horsepower compounded steam turbine,built by Newport News Shipbuilding & Dry Dock Company. The steam turbineis coupled to an articulated double reduction main propulsion gear setbuilt by General Electric Company. The turbine oil has shown excellentservice in this test.

EXAMPLE V A higher viscositylu-bricating oil was prepared by blendingabout 80 weight percent of the base oil of Exampie 1 with about 20weight percent of a (propane) deasphalted, MEK dewaxed, phenolextracted, clay contacted residuum from a Mid-Continent crude to give abase oil having a viscosity at 210 F. of about 65 S.U.S. To this baseoil was added 0.34 weight percent zinc dialkyl dithiophosphate, 0.15Weight percent barium dinonyl naphthalene sulfonate, and 0.05 weightpercent C 0X0 mercaptoacetic acid. This oil passed the ASDM D665 seawater rust test.

Similar oils of higher viscosity containing: (a) 0.05 sulfonate and 0.03C Oxo SCH COOH or; (b) 0.10 sulfonate and 0.04 C 0x0 SCH COOH havepassed the above rust test.

The following claims set forth that part of the above describedinvention for which patent protection is respectfully requested.

What is claimed is:

1. A non-emulsifying lubricating composition comprising a majorproportion of a mineral lubricating oil and in the range of 0.005 to 1.0Weight percent each of a branched C to C alkyl mercaptoacetic acid andan alkaline earth metal salt of C to C branched chain dialkylnaphthalenesulfonate as the sole sulfonate, the alkaline earth metal being selectedfrom the group consisting of calcium and barium.

2. The lubricating composition of claim 1 comprising, in additionthereto, 0.05 to 2.0 weight percent of an oil soluble zinc C to Cdialkyl dithiophosphate.

3. The lubricating composition according to claim 1 wherein the alkylradical of the alkyl mercaptoacetic 6 acid is a highly branched radicalhaving at least three branched groups.

4. The lubricating composition according to claim 1 wherein themercaptoacetic acid is a highly branched C mercaptoacetic acid and thesulfonate is a branched chain dinonylnaphthalene sulfonate.

5. The lubricating composition according to claim 1 wherein said alkylmercaptoacetic acid is a C Oxo mercaptoacetic acid and wherein saiddialkyl naphthalene sulfonate is a barium dinonylnaphthalene sulfonate.

6. The lubricating composition according to claim 2 wherein said alkylmercaptoacetic acid is a C Oxo mercaptoacetic acid and wherein saiddialkyl naphthalene sulfonate is a barium dinonylnaphthalene sulfonate.

References Cited in the file of this.patent UNITED STATES PATENTS2,364,284 Freuler Dec. 5, 1944 2,491,066 Wasson et a1. Dec. 13, 19492,693,448 Landis et al. Nov. 2, 1954 2,739,125 Myers et al Mar. 20, 19562,764,548 King et a1 Sept. 25, 1956 2,779,784 Sharrah Jan. 29, 1957FOREIGN PATENTS 659,072 Great Britain Oct. 17, 1951 689,759 GreatBritain Apr. 1, 1953 526,206 Canada June 12, 1956

1. A NON-EMULSIFYING LUBRICATING COMPOSITION COMPRISING A MAJORPROPORTION OF A MINERAL LUBRICATING OIL AND IN THE RANGE OF 0.005 TO 1.0WEIGHT PERCENT EACH OF A BRANCHED C9 TO C17 ALKYL MERCAPTOACETIC ACIDAND AN ALKALINE EARTH SALT OF C6 TO C12 BRANCHED CHAINDIALKYLNAPHTHALENE SULFONATE AS THE SOLE SULFONATE, THE ALKALINE EARTHMETAL BEING SELECTED FROM THE GROUP CONSISTING OF CALCIUM AND BARIUM.